An Italian patent application, assigned to the present application's assignee, discloses a MOSFET implemented current by-pass device useful in photovoltaic panel conversion plants or similar DC power distribution networks and a polarity inversion safety device in battery powered systems that can be fabricated in a compact highly reliable system-in-package form. The device is based on the use of a high multiplication factor (HMF) inductive voltage booster. The voltage booster boosts a voltage from about 50-100 mV up to several Volts, the voltage being applied to the gate of a low on-resistance power MOSFET that is connected in parallel to a DC source or string of DC sources to be eventually by-passed. The applied voltage is for turning the MOSFET ON and maintaining it in conduction, assisted by a start-up low multiplication factor (LMF) charge pump made with low threshold transistors, and for providing a supply voltage to a polarity inversion detecting comparator of the drain-to-source voltage difference of the MOSFET.
In the event of a fire, it may be a safety risk to have photovoltaic DC power generating modules connected in series since they build up a significant DC voltage, the voltage being coupled to the input of a DC-AC inverter and converted to standard grid frequency and voltage. The modules may present an electrocution risk for fire-fighting operators, notwithstanding that an “anti-islanding” safety system may have disconnected the photovoltaic conversion plant from the grid and disabled the main DC-AC inverter of the generating plant.
Italian patent application No. VA2010A000025, of Mar. 15, 2010, discloses an approach to such a safety problem based on the deployment in each panel of a transceiver for receiving a disabling command from a remote location and a circuit for disabling a DC-DC converter with MPPT control installed in each panel.